JP3003808B2 - Micro lens and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microlens which retains an excellent shape having a high light-collecting property and has good transparency, and a method for producing the same.

[0002]

2. Description of the Related Art Generally, an image sensor such as a CCD image pickup device has a structure in which a sensor portion for sensing light and a portion where light is not required are arranged on a substrate. However, they have the disadvantages of poor light sensitivity and low light sensitivity.

[0003] Therefore, in order to improve such a drawback, it has been proposed that, for example, incident light is focused on a sensor portion to improve light sensitivity, and that a microlens is formed for each sensor portion of an image sensor. Attempted.

Meanwhile, a phenol novolak resin is known as a material for forming the microlens. As a forming method, for example, a phenol novolak resin sensitive to far ultraviolet light is applied on an image sensor, and the glass transition is performed. After heating at a temperature above the point to flow and flatten the surface, apply phenol novolak resin again, selectively form a phenol novolak resin pattern on the sensor part by photolithography technology, and again A method is known in which a pattern is flowed at a temperature equal to or higher than the glass transition point, and a hemispherical microlens is formed by surface tension.

However, when the phenol novolak resin is used as a material for forming a microlens, the shape of the hemispherical microlens formed tends to change due to the heating temperature, and the shape of the microlens having excellent light condensing is obtained. Is difficult, and a problem arises in that a stable microlens shape cannot be formed. In addition, phenol novolak resins are liable to be colored by light irradiation or heat treatment, tend to deteriorate in transparency, and have a drawback that they do not have sufficient properties as a practical microlens forming material.

[0006]

SUMMARY OF THE INVENTION The present invention overcomes the drawbacks of a microlens obtained by using such a conventional microlens-forming material, retains an excellent shape with a high light-collecting power, and is transparent. The purpose of the present invention is to provide a microlens having good properties.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies to develop the above-mentioned good microlens, and as a result, have found that a specific copolymer, a quinonediazide group-containing compound, a thermosetting resin and It has been found that the object can be achieved by forming from a composition containing a specific triazine compound in some cases, and the present invention has been completed based on this finding.

That is, the present invention relates to (A) a copolymer of hydroxystyrene and methyl methacrylate, (B) a compound containing a quinonediazide group, (C) a thermosetting resin, and optionally (D) a general formula (I)

Embedded image (Wherein Z in the formula is a 4-alkoxyphenyl group or a group in which a benzene ring is condensed therewith). The present invention provides a microlens formed from a positive photoresist composition containing a triazine compound represented by the formula:

In the positive photoresist composition used for forming the microlens of the present invention, (A)
The copolymer of hydroxystyrene and methyl methacrylate used as the component has the general formula (II)

Embedded image (Where n and m in the formula indicate the degree of polymerization), and can be easily produced by copolymerizing hydroxystyrene and methyl methacrylate in the presence of a known radical polymerization initiator.

In this copolymer, the amount of hydroxystyrene units in the copolymer affects the developability of the obtained positive photoresist composition. The molar ratio n: m to the methacrylate unit is from 1: 9 to 9:
1, preferably in the range of 3: 7 to 7: 3.

When the amount of the hydroxystyrene unit is larger than the above range, the pattern shape is deteriorated and the transparency is lowered, and when it is smaller than the above range, the developability tends to be lowered, which is not preferable.

The amount of the hydroxystyrene unit affects the developability because the developability depends on the amount of hydroxyl groups in the copolymer, and it is important to adjust the amount. is there. As a method of adjusting the amount of the hydroxyl group, in addition to the method of controlling the ratio of the hydroxystyrene unit and the methyl methacrylate unit as described above, while heating the copolymer and, for example, hexamethyldisilazane or the like Reaction at a specific ratio in dioxane or α-naphthalenesulfonyl chloride,
By reacting sulfonic acid derivatives such as acetylaminobenzenesulfonyl chloride and 4-toluenesulfonyl chloride in dimethylacetamide at a specific ratio, the hydroxyl groups in the copolymer are silylated, acylated or sulfonylated to form a copolymer. The amount of hydroxyl groups in the coalescence may be adjusted.

In the above photoresist composition, the copolymer has a weight average molecular weight of 5,000 to 2,000.
It is practical to use one having a weight average molecular weight of 500, preferably 6,000 to 15,000.
If it is less than 0, a good pattern shape cannot be obtained, and if it exceeds 20,000, the developability tends to decrease.

In the above photoresist composition, (B)
The quinonediazide group-containing compound used as a component is
Used as a photosensitive component, as the quinonediazide group-containing compound, for example, sulfonic acid of quinonediazides such as o-benzoquinonediazide, o-anthraquinonediazide, and a compound having a phenolic hydroxyl group or an amino group, Completely esterified, partially or completely amidated, and the like can be mentioned. Examples of the compound having a phenolic hydroxyl group or an amino group include, for example, 2,3,4-trihydroxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, 2,3,4,4'-tetrahydroxybenzophenone, etc. Polyhydroxybenzophenone, alkyl gallate, aryl gallate, phenol, phenolic resin, p-methoxyphenol, dimethylphenol,
Hydroquinone, polyhydroxydiphenylalkane, polyhydroxydiphenylalkene, bisphenol A,
α, α ', α "-tris (4-hydroxyphenyl)-
1,3,5-triisopropylbenzene, 1- [1-
(4-Hydroxyphenyl) isopropyl] -4-
[1,1-bis (4-hydroxyphenyl) ethyl] benzene, tris (hydroxyphenyl) methane or a methyl-substituted product thereof, naphthol, pyrocatechol, pyrogallol, pyrogallol monomethyl ether, pyrogallol-1,3-dimethyl ether, gallic acid, Examples thereof include gallic acid, aniline, and p-aminodiphenylamine which are esterified or etherified while leaving a part of the hydroxyl group.
Particularly preferred quinonediazide group-containing compounds are polyhydroxybenzophenone and naphthoquinone-1,2-diazido-5-sulfonyl chloride or naphthoquinone-1,2.
-Esterified and partially esterified compounds with -diazido-4-sulfonyl chloride, particularly preferably those having an average degree of esterification of 70% or more.

In the above photoresist composition,
As the component (B), one or two or more photosensitive components comprising the above-mentioned quinonediazide group-containing compound may be contained.

The quinonediazide group-containing compound can be prepared, for example, by mixing the above-mentioned polyhydroxybenzophenone with naphthoquinone-1,2-diazide-5-sulfonyl chloride or naphthoquinone-1,2-diazide-4-sulfonyl chloride in a suitable solvent such as dioxane. It can be produced by condensing in the presence of an alkali such as triethanolamine, an alkali carbonate or an alkali hydrogen carbonate, followed by complete esterification or partial esterification.

In the above photoresist composition, (C)
Examples of the thermosetting resin used as a component include, for example, a melamine resin, a urea resin, an alkoxymethylated melamine resin, an alkoxymethylated urea resin, and among them, particularly, an alkoxymethylated urea resin and an alkoxymethyl resin. Melamine resin is preferred because it gives a positive photoresist composition having excellent stability.

The alkoxymethylated urea resin and the alkoxymethylated melamine resin can be obtained by converting a methylol group of a known methylolated urea resin or a methylolated melamine resin into an alkoxymethyl group. The type of the alkoxymethyl group is not particularly limited, and examples thereof include a methoxymethyl group, an ethoxymethyl group, a propoxymethyl group, and a butoxymethyl group. -032, Nikarac Mx-706, Nikarac Mx-708, Nikarac Mx-40, Nikarac Mx-31, Nikarac Ms-11, Nikarac Mw
-22, Nikarac Mw-30 (manufactured by Sanwa Chemical Co., Ltd.) and other corresponding urea resins can be preferably used. These alkoxymethylated urea resins or melamine resins may be used alone or in combination of two or more.

Regarding the mixing ratio of each component in the photoresist composition, the copolymer (A)
The quinonediazide group-containing compound (B) is used in an amount of 10 to 30 parts by weight, preferably 15 to 25 parts by weight, and the thermosetting resin (C) is used in an amount of 1 to 20 parts by weight.
Preferably, it is used in a proportion of 2 to 12 parts by weight. If the mixing ratio of the component (B) and the component (C) is outside the above range, it is difficult to obtain a positive photoresist composition which gives a microlens having excellent shape and transparency, which is not preferable.

Further, the photoresist composition may optionally contain, as a component (D), a triazine compound represented by the general formula (I) in addition to the components (A), (B) and (C). It can be contained. This makes it possible to stably obtain a microlens having a shape exhibiting excellent light collecting properties.

Examples of the triazine compound represented by the above general formula (I) include 2- (4-methoxyphenyl)
-4,6-bis (trichloromethyl) -1,3,5-triazine, 2- (4-ethoxyphenyl) -4,6-bis (trichloromethyl) -1,3,5-triazine,
-(4-propoxyphenyl) -4,6-bis (trichloromethyl) -1,3,5-triazine, 2- (4-butoxyphenyl) -4,6-bis (trichloromethyl)
-1,3,5-triazine, 2- (4-methoxynaphthyl) -4,6-bis (trichloromethyl) -1,3,5
-Triazine, 2- (4-ethoxynaphthyl) -4,6
-Bis (trichloromethyl) -1,3,5-triazine, 2- (4-propoxynaphthyl) -4,6-bis (trichloromethyl) -1,3,5-triazine, 2-
(4-butoxynaphthyl) -4,6-bis (trichloromethyl) -1,3,5-triazine and the like. These triazine compounds may be used alone or in combination of two or more.

These triazine compounds can be obtained by using the above (A)
It is desirable to add 0.5 to 5 parts by weight, preferably 0.8 to 3 parts by weight, based on 100 parts by weight of the component copolymer. If the amount is less than 0.5 part by weight, the composition easily flows in a microlens shape, and the effect obtained by blending the component (D) is not sufficiently exhibited. If the amount exceeds 5 parts by weight, a practical microlens shape is obtained. It becomes difficult and is not preferred.

The above-mentioned photoresist composition is usually used in the form of a solution by dissolving the above-mentioned components (A), (B) and (C) and, if necessary, component (D) in an organic solvent. As the organic solvent used at this time, for example, acetone,
Ketones such as methyl ethyl ketone, cyclohexanone, isoamyl ketone; polyhydric alcohols such as ethylene glycol, propylene glycol, ethylene glycol monoacetate, diethylene glycol or diethylene glycol monoacetate monomethyl ether, monopropyl ether, monobutyl ether or monophenyl ether and derivatives thereof Cyclic ethers such as dioxane; and esters such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, methyl pyruvate and ethyl pyruvate. These may be used alone or in combination of two or more.

[0024] Compatible additives such as additional resins, plasticizers and stabilizers can be added to the photoresist composition as long as the object of the present invention is not impaired.

Next, a method of forming a microlens using the solution of the positive photoresist composition thus prepared will be described. First, a flattening film is provided on a silicone wafer on which an image element is formed. After the surface is flattened, a solution of the positive photoresist composition is applied by a spinner or the like, and dried to form a film having a thickness of 1.0 to 4.
A resist film of about 0 μm is formed. Next, after selectively irradiating this with actinic light, it is developed using an aqueous solution of an organic alkali such as an aqueous solution of tetramethylammonium or an aqueous solution of an inorganic alkali such as sodium hydroxide, potassium hydroxide, sodium metasilicate, or sodium phosphate. By performing the treatment, a pattern is formed by dissolving and removing the irradiated portion of the actinic ray, then irradiating the entire surface with ultraviolet rays for about 1 to 5 minutes, and then heating at a temperature of 100 to 300 ° C. for about 2 to 15 minutes. Thereby, the pattern is fluidized to form hemispherical microlenses.

[0026]

The microlens of the present invention has the characteristics that it is excellent in transparency, has a very good hemispherical shape obtained by heating, and has a high light-collecting property. , Is not greatly affected by the heating temperature, once it is fluidized to obtain a hemispherical shape, the shape does not change even if the heating temperature is increased, and the fluidization does not proceed, so the shape is excellent, It is stable and can be formed independently without contact between adjacent microlenses, so that it is extremely practical.

[0027]

Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

Example 1 Marcalinker CMM (Maruzen Petrochemical Co., Ltd.), a copolymer of hydroxystyrene and methyl methacrylate
[Hydroxystyrene unit: methyl methacrylate unit = 1: 1 (molar ratio), weight average molecular weight 9000] 300
0 g is dissolved in 10,000 g of dioxane, and 550 g of hexamethyldisilazane and triethylamine 2 are added to the solution obtained.
After adding 8 g and reacting at 90 ° C. for 48 hours, the reaction solution was distilled under reduced pressure to remove dioxane in the solution, and the solution obtained by replacing the solvent with ethylene glycol monoethyl ether acetate was added to gallic acid. Propyl 1
A coating solution was prepared by mixing 600 g of a reaction product of 3 mol of naphthoquinone-1,2-diazide-5-sulfonyl chloride and 300 g of Nicalac Mw-30 (manufactured by Sanwa Chemical Co., Ltd.).

The prepared coating solution is applied to a silicon wafer having a surface on which an image element is to be formed, the surface of which is flattened with a copolymer of glycidyl methacrylate and methyl methacrylate, for 3000 minutes.
After applying by a spinner for 40 seconds at rpm and drying at 110 ° C. for 90 seconds, the reduced projection exposure apparatus NSR-1
A pattern was formed by irradiating actinic rays with 505G4D (manufactured by Nikon Corporation) through a mask, and then performing paddle development with a 2.38% by weight aqueous solution of tetramethylammonium hydroxide for 6.5 seconds.

The PLA-50 is applied to the formed pattern.
After irradiating the entire surface with ultraviolet rays by 0F (manufactured by Canon Inc.), and heating at 150 ° C. for 5 minutes on a hot plate, a lens having a shape excellent in light condensing properties and a microlens having good transparency adjacent thereto is provided. They were formed independently without contact by the flow of each other.

Example 2 The amount of Nicalac Mw-30 used in the preparation of the coating solution used in Example 1 was changed to 90 g, and
A microlens was prepared in the same manner as in Example 1 except that a coating solution prepared by blending 30 g of (4-methoxyphenyl) -4,6-bis (trichloromethyl) -1,3,5-triazine was used. As a result, an extremely practical microlens having a shape with more excellent light collecting properties was formed.

Example 3 DE-3 [manufactured by Tokyo Ohka Kogyo Co., Ltd.] which is an inorganic developer containing sodium metasilicate instead of the 2.38% by weight aqueous solution of tetramethylammonium hydroxide used in Example 1 Was used to produce microlenses in the same manner as in Example 1 except that immersion development was performed for 150 seconds. As a result, good microlenses were formed as in Example 1.

Example 4 Markerlinker-CMM which is a copolymer of hydroxystyrene and methyl methacrylate [Maruzen Petrochemical Co., Ltd.
[Hydroxystyrene unit: methyl methacrylate unit = 1: 1 (molar ratio), weight average molecular weight 9000] 2
000 g and α-naphthalenesulfonyl chloride 105 g
Was dissolved in 10000 g of dimethylacetamide, and 8 g of triethylamine in a 25% by weight dimethylacetamide solution was added. After reacting at room temperature for 5 hours, the precipitate was separated by filtration and the filtrate was added to water. The reaction product was separated by filtration, washed with water and dried. Next, 1 mol of 2,3,4-trihydroxybenzophenone and naphthoquinone-1,2-diazide-5- were added to a solution obtained by dissolving the obtained dried product in ethylene glycol monoethyl ether acetate.
400 g of a reaction product with 3 mol of sulfonyl chloride and Nicalac Mw-30 [manufactured by Sanwa Chemical Co., Ltd.] 200
Example 1 except that a coating solution prepared by blending g was used.
As a result, a good microlens was formed in the same manner as in Example 1.

Example 5 α-Naphthalenesulfonyl chloride 1 used in Example 4
Microlenses were formed in the same manner as in Example 4 except that 05 g and 8 g of triethylamine were replaced with 320 g of 4-acetylaminobenzenesulfonyl chloride and 23 g of triethylamine, respectively. As a result, good microlenses were formed as in Example 1. Was done.

Example 6 α-Naphthalenesulfonyl chloride 1 used in Example 4
05 g, 8 g of triethylamine and 1 mol of 2,3,4-trihydroxybenzophenone were added to 175 g of 4-toluenesulfonyl chloride and 15 g of triethylamine, respectively.
A microlens was formed in the same manner as in Example 4 except that the amount was changed to 1 mol of propyl gallate, and a good microlens was formed as in Example 1.

Continuation of the front page (56) References JP-A-59-113435 (JP, A) JP-A-2-217855 (JP, A) JP-A-60-39642 (JP, A) JP-A-63-313150 (JP, A) JP-A-63-271346 (JP, A) JP-A-2-291559 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02B 3/00 G02B 1/04 G03F 7/022 G03F 7/033 G03F 7/40

Claims (9)

(57) [Claims] 1. A microlens formed from a positive photoresist composition comprising (A) a copolymer of hydroxystyrene and methyl methacrylate, (B) a compound containing a quinonediazide group, and (C) a thermosetting resin. . 2. A copolymer of (A) hydroxystyrene and methyl methacrylate, (B) a quinonediazide group-containing compound, (C) a thermosetting resin, and (D) a general formula: (Wherein Z in the formula is a 4-alkoxyphenyl group or a group in which a benzene ring is condensed thereto). A microlens formed from a positive photoresist composition containing a triazine compound represented by the formula: 3. The microlens formed from the positive photoresist composition according to claim 1, wherein the molar ratio of the hydroxystyrene unit to the methyl methacrylate unit in the component (A) is 1: 9 to 9: 1. 4. The microlens formed from the positive photoresist composition according to claim 1, wherein component (A) is obtained by silylating, acylating or sulfonylating a hydroxyl group in the copolymer. . 5. The positive photoresist according to claim 1, wherein the component (B) is an esterified product of a compound having a phenolic hydroxyl group or an amino group and naphthoquinone-1,2-diazide-5 or 4-sulfonyl chloride. A microlens formed from the composition. 6. The microlens formed from the positive photoresist composition according to claim 1, wherein the component (C) is at least one selected from an alkoxymethylated urea resin and an alkoxymethylated melamine resin. 7. Component (B) based on 100 parts by weight of component (A)
3. A microlens formed from the positive photoresist composition according to claim 1, wherein 10 to 30 parts by weight of the component and 1 to 20 parts by weight of the component (C) are blended. 8. The composition of (D) with respect to 100 parts by weight of the component (A)
3. A microlens formed from the positive photoresist composition according to claim 2, comprising 0.5 to 5 parts by weight of a component. 9. A flattening film is provided on a substrate, and the positive photoresist composition according to claim 1 is applied on the flattening film and dried to form a resist film. A method for manufacturing a microlens, comprising selectively irradiating a film with actinic rays, forming a resist pattern by alkali development, irradiating the entire surface with ultraviolet rays, and further performing a heat treatment.